1. Field of the Invention
The invention relates to an LED (light emitting diode) bulb, and more particularly to an omnidirectional LED bulb.
2. Brief Description of the Prior Art
A conventional LED bulb disclosed in the U.S. Pat. No. 8,567,990 includes mainly a substrate which is attached to one edge of a radiator. A cover is provided to shield the substrate. Heat-radiating fins may be provided on the other edge of the radiator and an air-cooling unit is provided inside the heat-radiating fins so as to achieve a free heat radiation. In the embodiments of U.S. Pat. No. 8,567,990, there is a case for storing a circuit part which is attached to the other edge of the radiator. The case has a cap to cover the same. With the airflow from the air-cooling unit, the heat-radiating fins become a part of the ventilation path to allow ventilation inside the radiator.
Another conventional LED bulb comprises a heat sink, an LED circuit board with LEDs, and a light-transmitting shell. An electrical connector is mounted on a rear terminal of the heat sink. The LED circuit board is mounted on a front surface of the heat sink. The shell is light-transmitting and mounted on the front surface of the heat sink to contain the LED circuit board. When the electrical connector is electrically connected to a socket, the LED circuit board receives a working voltage for activating the LEDs to emit light forward. However, the LEDs shall emit light forward only. The LEDs fail to emit light laterally or backward due to the heat sink mounted behind the LEDs to block the emitted light. As a result, the conventional LED bulb is not capable of emitting uniform and omnidirectional illumination.